Chris,
David said at a recent seminar that he plans on making the principles into a book at some point in the future (no timeline; the next book is going to be based on his "Leveraging Focus and Vision" seminar) - so he doesn't want to post archives of the principles / newsletters online, or else there'd be no (or at least less) reason to buy the book. I know this is disappointing to those of us who came to the newsletters relatively late, but, given the amount of great information that he does post for free, I figure I can't begrudge him holding on to some of the good stuff!